Reinforced block made from composite material and method for reinforcing a composite block

ABSTRACT

A block including at least one glass ply at least partially covering an outer surface of a core made from composite material. A method for reinforcing a block made from a composite material, including a glass ply placed in a mould, such as to cover the base of the mould; the block is positioned in the mould; the edges of the glass ply are folded such that the glass ply is moulded to the outer edge of the block; the mould is closed with a cover; the block housed inside the mould is cured in an oven such as to polymerize the glass ply; and the glass-ply-covered block is recovered.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/FR2008/051770 International Filing Date, 1 Oct. 2008, whichdesignated the United States of America, and which InternationalApplication was published under PCT Article 21 (s) as WO Publication No.WO2009/053573 A2 and which claims priority from, and the benefit of,French Application No. 200758207 filed on 11 Oct. 2007, the disclosuresof which are incorporated herein by reference in their entireties.

BACKGROUND

The aspects of the disclosed embodiments relate to a block in compositematerial which is reinforced in order to withstand impacts and otherexternal stresses. The disclosed embodiments particularly relate to ablock in composite material which is intended to be placed on the uppersurface of an aircraft wing in order to restore the aerofoil section inthe region where said wing is fixed to the aircraft fuselage. Thedisclosed embodiments relate also to a method for reinforcing a block incomposite material.

SUMMARY

It is currently known in many fields to replace some components,previously made of metallic material, with components in compositematerial, notably in order to reduce the total mass of the deviceprovided with one or more of these components. Thus, in the aeronauticalfield, many components, such as beams, covering panel etc. are now madeof composite material. If it enables to get good results from the pointof view of the final aircraft mass, the components in composite materialcan sometimes have an insufficient resistance to the charges to bewithstood or to the environmental stresses.

It is notably the case when transition blocks are used in the regionwhere an aircraft wing is fixed to said aircraft fuselage, and areintended to restore the aerofoil section of the wing in the fixationregion. Such blocks in composite material are described in the patent FR2 869 872. The transition block in composite material is located on theupper surface of the wing and is submitted to bad weather and to otherexternal stresses. The transition block is made for example of apolymethacrylimid foam, that is hard and light, which facilitates itshandling and installation on the upper surface of an aircraft wing.

The external surface of said block in composite material remains howevergranular, even after the application of one or more protecting paintlayer(s).

Moreover, it frequently happens that the block in composite material ismarked, indeed damaged, at the time of the fixation onto the aircraftwing. The block is often dented by the knee prints of the installationworkers, by pots of paint used for covering the blocks etc. The dents onthe external surface of the block tend to reduce the aerodynamicperformance of the aircraft, which notably increases the fuelconsumption of the aircraft.

One aspect of the disclosed embodiments is to increase the resistance ofa block in composite material, such as that used as a transition blockat the junction between the wing and the fuselage of an aircraft.

To this end, according to the disclosed embodiments, it is proposed tocover the block in composite material with one or more layer(s) of glasswhich conform(s) to the external profile of the block. The layers ofglass are advantageously polymerized on the central mass in compositematerial. Thus, whatever its shape may be, the block is entirely coveredwith layers of glass which smooth the external surface and reinforce itagainst the external stresses. The disclosed embodiments aim atproviding a method for reinforcing the block, wherein said block incomposite material is covered with one or more layer(s) of glass. Themethod according to the disclosed embodiments uses a mould able towithstand high temperatures and to be dismounted in order to free theblock once the layers of glass are polymerized on the central mass incomposite material.

An aspect of the disclosed embodiments is thus a block intended to befixed to the supper surface of an aircraft wing, wherein it comprises acore in composite material and at least one folded layer of glasscovering at least partially an external surface, or wall, of the core incomposite material.

According to embodiment examples of the block according to the disclosedembodiments, it is possible to provide all or part of the followingadditional characteristics:

-   -   the block comprises three folded layers of glass superposed so        that three successive layers are formed around the core in        composite material;    -   the composite material forming the block core is a        polymethacrylimid foam.

The disclosed embodiments relate also a method for reinforcing a blockin composite material, wherein it comprises the following steps:

-   -   a first lower folded layer of glass is placed into a mould, in        order to cover a mould bottom and in order that the edges of the        lower folded layer of glass project from the lateral walls of        said mould;    -   the block is placed into the mould, with the external side        facing the outside of the mould.    -   the lower folded layer of glass is folded over the block, so        that the folded layer of glass conforms to the external profile        of the block;    -   the mould is closed by means a cover;    -   the block in the mould is fired in an oven in order to        polymerize the folded layer of glass;    -   the block covered with the folded layer of glass is removed.

According to some embodiment examples of the method according to thedisclosed embodiments, it is possible to implement all or part of thefollowing additional steps:

-   -   a second lower folded layer of glass is placed into the mould in        order to cover the first lower folded layer of glass; a third        lower folded layer of glass is placed in the same way over the        second lower folded layer of glass; the third lower folded layer        of glass is leveled at the joint plane; the three lower folded        layers of glass are successively folded over the external side        of the block. In the case when the dimensions of the block and        of the mould are strictly superior to the dimensions of the        folded strips of glass used, a number of strips are used in an        adjacent arrangement in the mould in order to form a given        folded layer of glass;    -   the external side of the bloc is covered with a first upper        folded layer of glass before placing said block into the mould.        Thus, if the dimensions of the lower folded layers of glass are        not sufficient for covering the entire surface of the block        core, the external side of said core is covered with the upper        folded layer(s) of glass, whereas the internal side and the        lateral walls of said block core are covered with the lower        folded layers of glass;    -   the block is fired in an oven in which the temperature is        progressively increased at a rate of 2° C./min until the        temperature level of 150° C.+/−20° C. is reached; the        temperature level is maintained for 2 hours, +/−15 min;    -   a mould with a bottom on which four lateral walls and a        removable cover are mounted, is used; after the firing step, the        cover and the four lateral walls are removed from the mould in        order to remove the block covered with folded layers of glass.

The disclosed embodiments will be better understood from the followingdescription and from the accompanying figures. These figures are givenas an indicative, but non-limitative illustration of the disclosedembodiments. In the figures:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a first example of a block incomposite material which can be covered with folded layers of glassaccording to the disclosed embodiments;

FIG. 2 is a schematic representation of a second example of a block incomposite material which can be covered with folded layers of glassaccording to the disclosed embodiments;

FIGS. 3A, 3B and 3C represent three sectional enlargements of the blockin FIG. 2, at the front tip, a central section and a back section,respectively;

FIG. 4 is a schematic representation of a cross section of a mould usedfor implementing the method according to the disclosed embodiments;

FIG. 5 is a schematic representation of a cross section of the mouldaccording to the disclosed embodiments in which the block to be coveredwith folded layers of glass is placed.

In the examples described below, it is referred only to transitionblocks to be fixed to the upper surface of an aircraft wing in order tofacilitate the passage of a joint from the means for fixing of the wingto the aircraft fuselage to the upper surface of said wing. Of course,the disclosed embodiments can also be applied to any other kind of blockin composite material, whatever its dimensions may be.

Such a transition block can have a length of several tenths of metersand a thickness which varies from one end of the block to the other.“Length” means the dimension of said block extending parallel to thelongitudinal axis of the block. “Thickness” means the dimension of theblock extending vertically to a plane in which the block extends.

Afterwards, “external side” means the block side facing the outside ofthe mould and “internal side” means the block side in contact with themould bottom. On the other hand, in use, the external side of the blockis fixed to the upper surface of the aircraft wing, and the internalside is submitted to external stresses.

DETAILED DESCRIPTION

In FIG. 1 it is represented a first example of the block 1 in compositematerial, which is intended to be fixed to the upper surface of anaircraft wing.

The block 1 comprises a beveled end 2, a second end 3 opposite thechamfered end 2 being a right end. Moreover, as it appears from thecross view I-I, the thickness E, e of the block 1 decreases widthwise.“Width” means the dimension of the block 1 which extends transversely tothe longitudinal axis A of the block 1.

In FIG. 2 it is represented a second example of a transition block 10,said block 10 having a constant thickness, but a width I, I′ whichdecreases from the first end 11 to a second end 12, both ends beingright ends, in contrast with a beveled end.

The block 10 comprises a core 13 in composite material covered with atleast one folded layer of glass, which increases the resistance of theblock 10 to external stresses.

In the method according to the disclosed embodiments, any block can becovered with one or more folded layer(s) of glass, whatever itsdimensions, form etc. may be.

To this end, according to the method of the disclosed embodiments, it isused a mould such as represented in FIG. 4.

The mould 100 comprises a bottom, or base 101, the internal side 102 ofwhich is intended to receive the block 10. “Internal side” means theside in an internal volume V of the mould 100. Said mould 100 comprisesotherwise four lateral walls 103 (only two lateral left and right wallsare visible in FIG. 4), said lateral walls 103 being removable in orderto be dismounted from the bottom 101. Moreover, the mould 100 comprisesa cover 104 able to be sealed on the upper ends 105 of the lateral walls103 in order to hermetically close the internal volume V of the mould100.

The internal volume V of the mould 10 is able to receive the block 10.

According to the method of the disclosed embodiments, a first lowerfolded layer of glass 14 is placed at the beginning against the internalwall 102 of the bottom 101 of the mould 100. The first lower foldedlayer of glass 14 conforms to the profile of the mould 100 and coversthe bottom 102 and the lateral walls 103 as far as the ends 105. Moreprecisely, the external edges 15 of the first lower folded layer ofglass are placed side by side against the ends 105 of the lateral walls103. the first lower folded layer of glass 15 is the layer intended tobe in contact with the outside with respect to the foam core 13 which itsurrounds.

Then a second lower folded layer of glass 116 is placed over the firstlower folded layer of glass 14. the edges 17 of the second lower foldedlayer of glass 16 cover the external edges 15 of the first lower foldedlayer of glass 14.

Then, a third lower folded layer of glass 18 is placed over the secondlower folded layer of glass which it surrounds.

The external edges 19 of the third lower folded layer of glass 18 areleveled at the ends 105 of the lateral walls 103 of the mould 100. Anexcessive thickness at the external side 21 of the core 13 of the block10 is thus avoided because the edges 15, 17, 19 of the folded layers ofglass 14, 16, 18 are folded against said external side 21.

The core 13 in composite material of the bock 10 is placed into theinternal volume V of the mould 100 so that the internal side 20 of saidcore 13 in composite material is placed against the internal wall 102 ofthe bottom 101 of the mould 100.

In the example represented in FIG. 5, the external side 21 of the core13 in composite material has been first covered with three superposedupper folded layers of glass 22. It enables to assure a tightness at thecore 103 of the block 10 while guaranteeing that the entire surface ofthe core 103 is covered with at least one folded layer of glass. Indeed,if the external side 21 of the core 13 in composite material is notcovered with its own folded layers of glass and if the dimensions of thelower folded layers of glass are not sufficient, it is possible that acentral portion of the core 13 of the block 10 is not covered once thelower folded layers of glass are folded over the external side of thecore 13 of the block 10.

Of course, the upper folded layers of glass 22 can be placed on theexternal side 21 of the core 13 in composite material only when thiscore has been placed into the mould 100 and before the edges 19, 17, 15of the lower folded layers 14, 16, 18 are folded over said external side21, even after folding said edges 19, 17, 15 over said external side 21.

When the core 13 in composite material is placed in the internal volumeV of the mould 100, the external edges 9 of the third lower folded layerof glass 18 is folded against the external wall 21 of the core 13 andthen against the external edges 17 of the second lower folded layer ofglass 16 and finally against the external edges 15 of the first lowerfolded layer of glass 14.

The folded layers of glass 14, 16, 18, 22 are thus draped over the foamcore 13 while conforming to the profile thereof.

Before folding the lower folded layers of glass 14, 16, 18 over theexternal wall 21 of the core 13, it is possible to cut all the angles ofthe folded layers of glass, or only some of them, with an angle of 45°in order to avoid an excessive overlapping of the folded layers of glass14, 16, 18 which could locally lead to a damageable excessive thickness.

The internal volume V of the mould 100 is then closed by means of thecover 104 which is fixed by any means to the lateral walls 103.

The mould 100 is then placed into an oven and heated up to 150° C. at arate of 2° C./min and then the mould is left at this temperature levelfor two hours.

The mould 100 is then removed from the oven and is left to cool down to60° by natural convection.

The mould 100 is opened in order to extract the block 10. To that end,the lateral walls 103 are dismounted from the bottom 101 in order toeasily remove the block 10 from said mould 100.

FIGS. 3A, 3B and 3C show different cross views of the block 10 coveredwith folded layers of glass according to the disclosed embodiments. Ofcourse, the block 10 can be covered with more or less folded layers ofglass, according to the thickness of said folded layers and according tothe purpose of the block.

Thus, in FIG. 3A, it is represented a longitudinal section of the frontend 12 of the block 10.

Three upper folded layers of glass 22 cover the external wall 21 of thecore 13 in composite material of the block 10 intended to be fixed tothe upper surface of an aircraft wing. The three lower folded layers ofglass 14, 16 and 18 conform to an external profile of the internal wall20 of the core 13 in composite material, intended to be submitted toexternal stresses. At this end 12, the upper folded layers covers thelower folded layers 14, 16, 18, which enables to assure a tightness ofthe core 13 in composite material by means of the glass protection.

In FIG. 3B, it is represented a longitudinal section of the block 10 atsome place of said block 10.

Thus, we can see the three upper folded layers 22 covering the externalside 21 of the core 13 of the block 10, as well as the three lowerfolded layers 14, 16, 18 covering the internal side 20 of said core 13.

In the example represented in FIG. 3B, each folded layer of glass 14,16, 18, 22 considered is formed by a number of bands of pre-impregnatedfabric successively placed in the same plane. Of course, if the bands ofpre-impregnated fabric used have sufficient dimensions, it is possibleto use one band for each folded layer. However, in the case of a block10 with big dimensions, the use of a number of bands of pre-impregnatedfabric for forming a given folded layer of glass enables to facilitatethe installation into the mould 100: instead of handling only one bandof pre-impregnated fabric with big dimensions for placing it against thebottom 102 of the mould 100 and against the lateral walls 103 of saidmould, over the entire length of said mould, a number of small bands ofpre-impregnated fabric are successively placed for covering the entireinternal surface of the mould 100.

In FIG. 3C, it is represented a cross section of the block 10 at someplace of said block 10, showing the core 13 in composite materialsurrounded with the succession of folded layers of glass 14, 16, 18 and22 forming a tight protecting shell around said core 13.

In the particular case of transition blocks intended to be fixed to theupper surface of an aircraft wing, each folded layer of glass hasadvantageously a thickness of 0.2 mm+/−0.05 mm.

1. A block intended to be fixed to the upper surface of an aircraftwing, comprising: a core in composite material; and at least one foldedlayer of glass entirely covering an external surface of the core incomposite material.
 2. The block according to claim 1, furthercomprising three folded layers of glass superposed so that threesuccessive layers are formed around the core in composite material. 3.The block according to claim 1, wherein the core in composite materialcomprises a polymethacrylimid foam.
 4. A method for reinforcing a blockin composite material, comprising; a first lower folded layer of glassis placed into a mold, in order to cover a mold bottom and in order thatedges of the lower folded layer of glass project from the lateral wallsof said mold; an external side of the block is covered with at least oneupper folded layer of glass; the block is placed into the mold; theedges of the first lower folded layer of glass are folded over theblock, so that the folded layer of glass conforms to the externalprofile of the block; the mold is closed by means a cover; the block inthe mold is fired in an oven in order to polymerize the folded layer ofglass; the block covered with the folded layer of glass is removed. 5.The method according to claim 4, further comprising: a second lowerfolded layer of glass is placed into the mold in order to cover thefirst lower folded layer of glass; a third lower folded layer of glassis placed in the same way over the second lower folded layer of glass;the third lower folded layer of glass is leveled at the joint plane; thethree lower folded layers of glass are successively folded over theexternal side of the block.
 6. The method according to claim 4, furthercomprising: the block is fired in an oven in which a temperature isprogressively increased at a rate of 2° C./min until the temperaturelevel of 150° C.+/−20° C. is reached; the temperature level ismaintained for 2 hours, +/−15 min;
 7. The method according to claim 4,further comprising: a mold with a bottom on which four lateral walls anda removable cover are mounted, is used; after the firing step, the coverand the four lateral walls of the mold are removed in order to removethe block covered with folded layers of glass.